A beam tracing method for interactive architectural acoustics

A difficult challenge in geometrical acoustic modeling is computing propagation paths from sound sources to receivers fast enough for interactive applications. This paper describes a beam tracing method that enables interactive updates of propagation paths from a stationary source to a moving receiver in large building interiors. During a precomputation phase, convex polyhedral beams traced from the location of each sound source are stored in a "beam tree" representing the regions of space reachable by potential sequences of transmissions, diffractions, and specular reflections at surfaces of a 3D polygonal model. Then, during an interactive phase, the precomputed beam tree(s) are used to generate propagation paths from the source(s) to any receiver location at interactive rates. The key features of this beam tracing method are (1) it scales to support large building environments, (2) it models propagation due to edge diffraction, (3) it finds all propagation paths up to a given termination criterion without exhaustive search or risk of under-sampling, and (4) it updates propagation paths at interactive rates. The method has been demonstrated to work effectively in interactive acoustic design and virtual walkthrough applications.     

Stereochemistry and reactivity of the HPA-imine Mannich intermediate

Homophthalic anhydride (HPA) typically reacts rapidly with benzalimines to afford the formal [4+2] adduct, a 1,2,3,4-tetrahydroisoquinolin-1-one-4-carboxylic acid. The stereochemical outcome of this reaction is consistent with an open transition state comprising an iminium species and enolized HPA, leading to a short-lived amino-anhydride intermediate. In the case of N-tert-butylbenzalimine, this Mannich-type intermediate, which would normally cyclize at low temperature to a single isomer of the delta-lactam, is intercepted by base treatment to afford beta-lactam products. A pathway featuring ketene formation followed by ring closure is implicated.     

The positive maximum principle on symmetric spaces

Positivity - We investigate the Courrège theorem in the context of linear operators that satisfy the positive maximum principle on a space of continuous functions over a symmetric space....     

Probing neutrino and Higgs sectors in $$\text{ SU(2) }_1 \times \text{ SU(2) }_2 \times \text{ U(1) }_Y $$ model with lepton-flavor non-universality

The neutrino and Higgs sectors in the \(\text{ SU(2) }_1 \times \text{ SU(2) }_2 \times \text{ U(1) }_Y \) model with lepton-flavor non-universality are discussed. We show that active neutrinos can get Majorana masses from radiative corrections, after adding only new singly charged Higgs bosons. The mechanism for the generation of neutrino masses is the same as in the Zee models. This also gives a hint to solving the dark matter problem based on similar ways discussed recently in many radiative neutrino mass models with dark matter. Except the active neutrinos, the appearance of singly charged Higgs bosons and dark matter does not affect significantly the physical spectrum of all particles in the original model. We indicate this point by investigating the Higgs sector in both cases before and after singly charged scalars are added into it. Many interesting properties of physical Higgs bosons, which were not shown previously, are explored. In particular, the mass matrices of charged and CP-odd Higgs fields are proportional to the coefficient of triple Higgs coupling \(\mu \). The mass eigenstates and eigenvalues in the CP-even Higgs sector are also presented. All couplings of the SM-like Higgs boson to normal fermions and gauge bosons are different from the SM predictions by a factor \(c_h\), which must satisfy the recent global fit of experimental data, namely \(0.995<|c_h|<1\). We have analyzed a more general diagonalization of gauge boson mass matrices, then we show that the ratio of the tangents of the W–\(W'\) and Z–\(Z'\) mixing angles is exactly the cosine of the Weinberg angle, implying that number of parameters is reduced by 1. Signals of new physics from decays of new heavy fermions and Higgs bosons at LHC and constraints of their masses are also discussed.     

Synthesis of bengamide E analogues and their cytotoxic activity

A series of bengamide E analogues were prepared from the corresponding polyketide chain and amino acids via amide coupling reactions. Opening of the polyketide chain lactone ring with α-aminolactams was successfully achieved under microwave irradiation in the presence of sodium 2-ethyl hexanoate. A cytotoxic activity evaluation against a panel of cancer cell lines (KB, HepG-2, Lu-1, MCF-7, HL-60 and Hela) indicated that the 2′R analogues were generally more cytotoxic than the 2′S analogues. Additionally, several analogues exhibited selective inhibition against various cancer cell lines: compounds 32a and 32b selectively inhibited MCF-7 cells, while 33b and 35b were more sensitive toward Lu-1 and HepG-2, respectively. Notably, some of the synthetic analogues possess cytotoxic activities with IC₅₀ values less than 1 µM.     

Chemical Constituents and Cytotoxic Activities of Stem Bark of Dialium cochinchinense

Chemistry of Natural Compounds -     

Hydrogen‐bonded chains in three cis‐dichloridoplatinum(II) complexes bearing piperidine and amine ligands

The crystal structures of cis‐dichlorido(ethylamine‐κN)(piperidine‐κN)platinum(II), [PtCl₂(C₂H₇N)(C₅H₁₁N)], (I), cis‐dichlorido(3‐methoxyaniline‐κN)(piperidine‐κN)platinum(II), [PtCl₂(C₅H₁₁N)(C₇H₉NO)], (II), and cis‐dichlorido(piperidine‐κN)(quinoline‐κN)platinum(II), [PtCl₂(C₅H₁₁N)(C₉H₇N)], (III), have been determined at 100 K in order to verify the influence of the nonpiperidine ligand on the geometry and crystal packing. The crystal packing is characterized by N—H...Cl hydrogen bonding, resulting in the formation of chains of molecules connected in a head‐to‐tail fashion. Hydrogen‐bonding interactions play a major role in the packing of (I), where the chains further aggregate into planes, but less so in the case of (II) and (III), where π–π stacking interactions are of greater importance.     

ChemInform Abstract: Experimental Detection and Theoretical Characterization of Germanium‐Doped Lithium Clusters LinGe (n = 1—7).

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.     

Synthesis and Crystal Structures of Dioxomolybdenum(VI) Complexes with ONS-Donor Ligands

Abstract  

Three dioxomolybdenum complexes namely dioxo(5-chlorosalicylaldehyde thiosemicarbazonato) dimethylsulfoxide molybdenum(VI) (C1), dioxo(5-chlorosalicylaldehyde 2-ethylthiosemicarbazonato) dimethylsulfoxide molybdenum(VI) (C2) and dioxo(5-chlorosalicylaldehyde N-phenylthiosemicarbazonato) dimethylsulfoxide molybdenum(VI) (C3) were prepared. The compounds all crystallize in the triclinic space group P-1 with a = 7.3184(3) ?, b = 7.5035(3) ?, c = 14.9713(6) ?, α = 85.005(2)°, β = 85.616(2)°, γ = 66.987(2)° for C1, a = 8.2339(1) ?, b = 10.1739(1) ?, c = 10.4017(1) ?, α = 78.486(1)°, β = 89.312(1)°, γ = 81.730(1)° for C2, a = 7.0591(1) ?, b = 9.5603(1) ?, c = 14.5762(2) ?, α = 76.280(1)°, β = 81.351(1)°, γ = 81.985(1)° for C3. In general, the overall geometry of these complexes can be regarded as a distorted octahedron with the tridentate thiosemicarbazonato ligands (L²⁻) bonded to the MoO₂ ²⁺ core, with the imine nitrogen, phenoxyl oxygen, sulfur atom and one of the terminal oxygen atoms of the dioxomolybdenum occupying the equatorial position. The sixth coordination site is occupied by the dimethylsulfoxide (DMSO) solvent molecules. The adjacent molecules of C1 are linked by N–H···N intermolecular hydrogen bonding, forming polymeric chains that run parallel to the bc plane. On the other hand, C2 is a discrete molecule while the molecules of C3 associate via weak N–H···O hydrogen bonding interaction to form a polymeric chain that runs along the a-axis.